After extensive testing we finally arrived to a stable version. I thank all those who have supported us with various tests.

(Always remember to install the CFW Submitted by removing the BluRay disc)
(For all those who incur 8002F157 error, it means you have not enabled MODE 'ON DEBUG ON via the qaflag and then have to do the deashing on the console) To correct this error: Install CFW 4.21 Rebug or CFW that allows you to activate the qa flag and the mode 'debugging. Upgrade to OFW 3:55 for two times in a row. (That's right, to install RECOVERY twice the OFW 3.55. Proceed with the installation of any other CFW's) OPTIONAL: It is recommended that after a successful installation of the CFW from recovery run "Rebuild Database and File System" for correct operation. (Thanks to franci97)